* test/src/comp-tests.el (61917-1): New test.
	* src/comp.c (syms_of_comp): New variable.
	* lisp/loadup.el: Store primitive arities before dumping.
	* lisp/emacs-lisp/comp.el (comp--func-arity): New function.
	(comp-emit-set-call-subr): Make use of `comp--func-arity'.

	* src/data.c (Ffset): Rename comp-enable-subr-trampolines into
	native-comp-enable-subr-trampolines.

	* src/comp.c (syms_of_comp): Likewise.

	* lisp/subr.el (comp-enable-subr-trampolines): Make
	comp-enable-subr-trampolines obsolete.

	* lisp/startup.el (native-comp-enable-subr-trampolines)
	(normal-top-level): Rename comp-enable-subr-trampolines into
	native-comp-enable-subr-trampolines.

	* lisp/loadup.el (dump-mode): Likewise.

	* lisp/emacs-lisp/comp.el (comp-subr-trampoline-install)
	(comp--trampoline-abs-filename): Likewise.

The new code to make interpreted closures safe-for-space introduced
a regression in `cconv-tests-interactive-closure-bug51695`, only seen
when using TEST_LOAD_EL.
A few other issues were found and fixed along the way.

* lisp/emacs-lisp/cconv.el (cconv-fv): Change calling convention and
focus on finding the free variables.
(cconv-make-interpreted-closure): New function.

* lisp/loadup.el: Use `compiled-function-p` rather than
`byte-code-function-p` so we also use safe-for-space interpreted
closures when we build with native compilation.
(internal-make-interpreted-closure-function):
Use `cconv-make-interpreted-closure`.

* src/eval.c (syms_of_eval): Rename `internal-filter-closure-env-function`
to `internal-make-interpreted-closure-function`.
(Ffunction): Let that new var build the actual closure.

* test/lisp/emacs-lisp/cconv-tests.el
(cconv-tests-interactive-closure-bug51695): Test specifically the
interpreted case.

Interpreted closures currently just grab a reference to the complete
lexical environment, so (lambda (x) (+ x y)) can end up looking like

    (closure ((foo ...) (y 7) (bar ...) ...)
             (x) (+ x y))

where the foo/bar/... bindings are not only useless but can prevent
the GC from collecting that memory (i.e. it's a representation that is
not "safe for space") and it can also make that closure "unwritable"
(or more specifically, it can cause the closure's print
representation to be u`read`able).

Compiled closures don't suffer from this problem because `cconv.el`
actually looks at the code and only stores in the compiled closure
those variables which are actually used.

So, we fix this discrepancy by letting the existing code in `cconv.el` tell
`Ffunction` which variables are actually used by the body of the
function such that it can filter out the irrelevant elements and
return a closure of the form:

    (closure ((y 7)) (x) (+ x y))

* lisp/loadup.el: Preload `cconv` and set
`internal-filter-closure-env-function` once we have a usable `cconv-fv`.

* lisp/emacs-lisp/bytecomp.el (byte-compile-preprocess): Adjust to new
calling convention of `cconv-closure-convert`.
(byte-compile-not-lexical-var-p): Delete function, moved to `cconv.el`.
(byte-compile-bind): Use `cconv--not-lexical-var-p`.

* lisp/emacs-lisp/cconv.el (cconv--dynbound-variables): New var.
(cconv-closure-convert): New arg `dynbound-vars`
(cconv--warn-unused-msg): Remove special case for `ignored`,
so we don't get confused when a function uses an argument called
`ignored`, e.g. holding a list of things that it should ignore.
(cconv--not-lexical-var-p): New function, moved from `bytecomp.el`.
Don't special case keywords and `nil` and `t` since they are already
`special-variable-p`.
(cconv--analyze-function): Use `cconv--not-lexical-var-p`.
(cconv--dynbindings): New dynbound var.
(cconv-analyze-form): Use `cconv--not-lexical-var-p`.
Remember in `cconv--dynbindings` the vars for which we used
dynamic scoping.
(cconv-analyze-form): Use `cconv--dynbound-variables` rather than
`byte-compile-bound-variables`.
(cconv-fv): New function.

* src/eval.c (Fsetq, eval_sub): Remove optimization designed when
`lexical-binding == nil` was the common case.
(Ffunction): Use `internal-filter-closure-env-function` when available.
(eval_sub, Ffuncall): Improve error info for `excessive_lisp_nesting`.
(internal-filter-closure-env-function): New defvar.

* lisp/loadup.el (featurep): Define the hash table in nativecomp
builds (but not otherwise).  A more natural place to define this
would be in comp.el, but comp.el isn't loaded yet when we load the
.elc file that updates comp--no-native-compile.  We could change
the load order and move the definition to comp.el, though.

* lisp/emacs-lisp/bytecomp.el (byte-compile-from-buffer): Allow
inhibiting nativecomp earlier (bug#57627).

* lisp/emacs-lisp/comp.el (native-compile-async-skip-p): Use the data.

The max-lisp-eval-depth limit is sufficient to prevent unbounded stack
growth including the specbind stack; simplify matters for the user by
not having them to worry about two different limits.  This change
turns max-specpdl-size into a harmless variable with no effects,
to keep existing code happy.

* lisp/subr.el (max-specpdl-size):
Define as an ordinary (but obsolete) dynamic variable.
* admin/grammars/Makefile.in:
* doc/lispintro/emacs-lisp-intro.texi (Loops & Recursion):
* doc/lispref/control.texi (Cleanups):
* doc/lispref/edebug.texi (Checking Whether to Stop):
* doc/lispref/eval.texi (Eval):
* doc/lispref/variables.texi (Local Variables):
* doc/misc/calc.texi (Recursion Depth):
Update documentation.
* etc/NEWS: Announce.
* src/eval.c
(FletX): Use safe iteration to guard against circular bindings list.
(syms_of_eval): Remove old max-specpdl-size definition.
(init_eval_once, restore_stack_limits, call_debugger)
(signal_or_quit, grow_specpdl_allocation):
* leim/Makefile.in:
* lisp/Makefile.in:
* lisp/calc/calc-stuff.el (calc-more-recursion-depth)
(calc-less-recursion-depth):
* lisp/calc/calc.el (calc-do):
* lisp/cedet/semantic/ede-grammar.el (ede-proj-makefile-insert-rules):
* lisp/cedet/semantic/grammar.el (semantic-grammar-batch-build-one-package):
* lisp/cus-start.el (standard):
* lisp/emacs-lisp/comp.el (comp--native-compile):
* lisp/emacs-lisp/edebug.el (edebug-max-depth):
(edebug-read-and-maybe-wrap-form, edebug-default-enter):
* lisp/emacs-lisp/regexp-opt.el (regexp-opt):
* lisp/eshell/esh-mode.el (eshell-mode):
* lisp/loadup.el (max-specpdl-size):
* lisp/mh-e/mh-e.el (mh-invisible-headers):
* lisp/net/shr.el (shr-insert-document, shr-descend):
* lisp/play/hanoi.el (hanoi-internal):
* lisp/progmodes/cperl-mode.el:
* src/fileio.c (Fdo_auto_save):
Remove references to and modifications of max-specpdl-size.

* lisp/subr.el (compiled-function-p): New function.

* test/lisp/international/ucs-normalize-tests.el (ucs-normalize-part1):
* lisp/gnus/gnus.el (gnus):
* lisp/mh-e/mh-e.el (mh-version):
* lisp/emacs-lisp/macroexp.el (emacs-startup-hook):
* lisp/emacs-lisp/cl-macs.el (compiled-function):
* lisp/emacs-lisp/bytecomp.el (byte-compile-fdefinition)
(byte-compile, display-call-tree):
* lisp/emacs-lisp/byte-opt.el (<toplevel-end>):
* lisp/emacs-lisp/advice.el (ad-compiled-p):
* lisp/cedet/semantic/bovine.el (semantic-bovinate-stream):
* lisp/loadup.el (macroexpand-all):
* admin/unidata/unidata-gen.el (unidata--ensure-compiled): Use it.

* lisp/emacs-lisp/pcase.el (pcase-mutually-exclusive-predicates):
Add entries for it.
(pcase--split-pred): Use it.

* lisp/help-fns.el (help-fns-function-description-header): Use `functionp`.
(help-fns--var-safe-local): Use `compiled-function-p`.